Tissue-removing catheter

ABSTRACT

A tissue-removing catheter for removing tissue in a body lumen includes a tube extending axially along the catheter. A junction box housing is located at a distal end of the tube. An elongate body extends distally from the junction box housing. The elongate body is sized and shaped to be received in the body lumen. A gear assembly is disposed in the junction box housing. The gear assembly engages the elongate body for rotating the elongate body. A tissue-removing element is mounted on a distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patent application Ser. No. 15/970,751, which was filed May 3, 2018, which claims the benefit of, and priority to, U.S. Provisional Application Ser. No. 62/500,867, which was filed May 3, 2017, and U.S. Patent Application Ser. No. 62/500,879, which was filed May 3, 2017, each of which is incorporated herein by reference in its entirety for all purposes.

FIELD

The present disclosure generally relates to a tissue-removing catheter, and more particular, to a rapid exchange guidewire assembly for a tissue-removing catheter.

BACKGROUND

Tissue-removing catheters are used to remove unwanted tissue in body lumens. As an example, atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the vessel. This process can be used to prepare lesions within a patient's coronary artery to facilitate percutaneous coronary angioplasty (PTCA) or stent delivery in patients with severely calcified coronary artery lesions. Atherectomy catheters typically employ a rotating element which is used to abrade or otherwise break up the unwanted tissue.

SUMMARY

In one aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises a tube extending axially along the catheter. A junction box housing is located at a distal end of the tube. An elongate body extends distally from the junction box housing. The elongate body is sized and shaped to be received in the body lumen. A gear assembly is disposed in the junction box housing. The gear assembly engages the elongate body for rotating the elongate body. A tissue-removing element is mounted on a distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a catheter of the present disclosure;

FIG. 2 is an enlarged elevation of a distal end portion of the catheter showing the catheter received in a guide catheter;

FIG. 3 is an enlarged fragmentary elevation of an intermediate portion of the catheter;

FIG. 4 is an enlarged fragmentary perspective view of the intermediate portion of the catheter received in the guide catheter and showing the guide catheter as transparent;

FIG. 5 is an enlarged fragmentary longitudinal vertical cross section of the intermediate portion of the catheter in FIG. 3;

FIG. 6 is an enlarged fragmentary longitudinal horizontal cross section of the intermediate portion of the catheter taken through line 6-6 in FIG. 3 with portions of a coil gear removed to show underlying detail;

FIG. 7 is an enlarged cross section taken through line 7-7 in FIG. 4;

FIG. 8 is an enlarged perspective view of a junction box of the catheter with the junction box shown as transparent to show a gear assembly inside the junction box;

FIG. 9 is a perspective view of the gear assembly;

FIG. 10 is an enlarged perspective view of a pinion gear of the gear assembly;

FIG. 11 is a cross section of the pinion gear;

FIG. 12 is an enlarged perspective view of a coil gear of the gear assembly;

FIG. 13 is a cross section of the coil gear;

FIG. 14 is an enlarged fragmentary longitudinal cross section of the distal end portion of the catheter in FIG. 2;

FIG. 15 is a cross section taken through line 5-5 in FIG. 2;

FIG. 16 is a fragmentary elevation of an isolation liner of the catheter with portions broken away to show internal detail;

FIG. 17 is an enlarged longitudinal cross section of a tissue-removing element of the catheter;

FIG. 18 is a fragmentary perspective of a catheter of another embodiment showing a housing of a junction box as transparent to show internal detail;

FIG. 19 is an elevation of the catheter in FIG. 18;

FIG. 20 is a longitudinal vertical cross section of the catheter in FIG. 19;

FIG. 21 is an enlarged perspective view of a pinion gear of the catheter in FIG. 18;

FIG. 22 is a cross section of the pinion gear in FIG. 21;

FIG. 23 is an enlarged perspective view of a coil gear of the catheter in FIG. 18; and

FIG. 24 is a cross section of the coil gear in FIG. 23.

Corresponding reference characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

Referring to the drawings, and in particular FIG. 1, a rotational tissue-removing catheter for removing tissue in a body lumen is generally indicated at reference number 10. The illustrated catheter 10 is a rotational atherectomy device suitable for removing (e.g., abrading, cutting, excising, ablating, etc.) occlusive tissue (e.g., embolic tissue, plaque tissue, atheroma, thrombolytic tissue, stenotic tissue, hyperplastic tissue, neoplastic tissue, etc.) from a vessel wall (e.g., coronary arterial wall, etc.). The catheter 10 may be used to facilitate percutaneous coronary angioplasty (PTCA) or the subsequent delivery of a stent. Features of the disclosed embodiments may also be suitable for treating chronic total occlusion (CTO) of blood vessels, and stenoses of other body lumens and other hyperplastic and neoplastic conditions in other body lumens, such as the ureter, the biliary duct, respiratory passages, the pancreatic duct, the lymphatic duct, and the like. Neoplastic cell growth will often occur as a result of a tumor surrounding and intruding into a body lumen. Removal of such material can thus be beneficial to maintain patency of the body lumen.

The catheter 10 is sized for being received in a blood vessel of a subject. Thus, the catheter 10 may have a maximum size of 3, 4, 5, 6, 7, 8, 9, 10, or 12 French (1, 1.3, 1.7, 2, 2.3, 2.7, 3, 3.3, or 4 mm) and may have a working length of 20, 30, 40, 60, 80, 100, 120, 150, 180 or 210 cm depending of the body lumen. While the remaining discussion is directed toward a catheter for removing tissue in blood vessels, it will be appreciated that the teachings of the present disclosure also apply to other types of tissue-removing catheters, including, but not limited to, catheters for penetrating and/or removing tissue from a variety of occlusive, stenotic, or hyperplastic material in a variety of body lumens.

Referring to FIGS. 1-3, the catheter 10 comprises an elongate outer layer 12 (broadly, an elongate body) disposed around an elongate inner liner 14. The outer layer 12 and inner liner 14 extend along a first longitudinal axis LA1 of the catheter from a junction box 15 to a distal end portion 18 of the catheter. The junction box 15 is located at an intermediate position along the catheter 10. In one embodiment, the junction box 15 is disposed about 20 to about 30 cm from the distal end of the catheter 10. A tissue-removing element 20 is disposed on a distal end of the outer layer 12 and is configured for rotation to remove tissue from a body lumen as will be explained in greater detail below. A sheath 22 (FIGS. 1 and 2) is disposed around the outer layer 12. The catheter 10 is sized and shaped for insertion into a body lumen of a subject. The sheath 22 isolates the body lumen from at least a portion of the outer layer 12 and inner liner 14. The sheath 22, outer layer 12, and inner liner 14 extend distally from the junction box 15. The inner liner 14 at least partially defines a guidewire lumen 24 for slidably receiving a guidewire 26 therein so that the catheter 10 can be advanced through the body lumen by traveling along the guidewire. The junction box 15 defines a guidewire port 39 which may also define a portion of the guidewire lumen 24. The guidewire port 39 provides an exit location for the guidewire at an intermediate location on the catheter 10. The guidewire 26 can be a standard 0.014 inch outer diameter guidewire. However, the junction box 15 allows for a shorter guidewire to be used with the catheter 10 because the guidewire exits the catheter 10 at the intermediate location on the catheter rather than extending along the entire working length of the catheter. In one embodiment, a guidewire having a length of less than about 200 cm (79 inches) may be used with the catheter 10. In one embodiment, a guidewire having a length of between about 150 cm (59 inches) and about 190 cm (75 inches) can be used. In certain embodiments, the inner liner 14 may have a lubricious inner surface for sliding over the guidewire 26 (e.g., a lubricious surface may be provided by a lubricious polymer layer or a lubricious coating). In the illustrated embodiment, the guidewire lumen 24 extends from the junction box 15 through the distal end portion 18 of the catheter 10 such that the guidewire 26 is extendable along only a portion of the working length of the catheter 10. In one embodiment, the overall working length of the catheter 10 may be between about 135 cm (53 inches) and about 142 cm (56 inches).

The catheter 10 further comprises a handle 40 secured at a proximal end portion 16 of the catheter. The handle 40 supports an actuator 42 (e.g., a lever, a button, a dial, a switch, or other device) configured for selectively actuating a motor 43 disposed in the handle to drive rotation of a drive 48 extending from the motor to the junction box 15. The drive 48 may have a length of about 100 cm to space the junction box 15 from the handle 40. The drive 48 may have other lengths without departing from the scope of the disclosure. In the illustrated embodiment the drive 48 is a coil shaft. A drive tube 27 encases the drive 48 and extends from the handle 40 to the junction box 15 to isolate the body lumen from the rotating drive. The drive tube 27 and drive 48 extend along a second longitudinal axis LA2 of the catheter 10 from the handle 40 to the junction box 15. The second longitudinal axis LA2 extends parallel to and spaced from the first longitudinal axis LA1. As will be explained in greater detail below, the junction box 15 transfers the torque of the drive 48 to the outer layer 12 for rotating the tissue-removing element 20 mounted at the distal end of the outer layer. A perfusion port 46 may also be disposed at the proximal end portion 16 of the catheter 10. The perfusion port 46 communicates with a space between a guide catheter 128 (FIGS. 4 and 7) and the drive tube 27 for delivering fluid (e.g., saline) to cool the rotating components in the junction box 15 and the rotating outer layer 12 during use.

It is understood that other suitable actuators, including but not limited to touchscreen actuators, wireless control actuators, automated actuators directed by a controller, etc., may be suitable to selectively actuate the motor in other embodiments. In some embodiments, a power supply may come from a battery (not shown) contained within the handle 40. In other embodiments, the power supply may come from an external source.

Referring to FIGS. 1, 3-5, and 8-13, the junction box 15 comprising a housing 90 enclosing a gear assembly 92 for operatively connecting the drive 48 to the outer layer 12. The gear assembly 92 in the junction box 15 is configured to effectively transfer motor torque from the motor 43 of up to about 13 mN.m. During the torque transfer, gears of the gear assembly 92 can rotate up to 10,000 RPMs and even up to 100,000 RPMs. The housing 90 comprises a rigid center portion 94 which generally surrounds the gear assembly 92, and flexible proximal and distal end portions 96 which provide a strain relief function for the housing to alleviate tension applied to the proximal and distal ends of the junction box 15 as the catheter 10 is bent during use. The rigid center portion 94 comprises a casing 98 and first and second bearing holders 100, 102 mounted on proximal and distal ends of the casing, respectively. The casing 98 may be formed from polyether ether ketone (PEEK).

The gear assembly 92 comprises a pinion gear 104 (broadly, a first gear) in mesh with a coil gear 106 (broadly, a second gear). The pinion gear 104 is attached to the drive 48 such that rotation of the drive causes rotation of the pinion gear which in turn rotates the coil gear. The coil gear 106 is attached to the outer layer 12 such that rotation of the coil gear causes rotation of the outer layer. In particular, the pinion gear 104 comprises a proximal attachment portion 108, a distal end portion 110, and a middle gear portion 112. The proximal attachment portion 108 includes a receptacle 114 that receives a distal end portion of the drive 48. The distal end portion of the drive 48 is fixed within the receptacle 114 to attach the drive to the pinion gear 104. In the illustrated embodiment the middle gear portion 112 includes ten (10) teeth 113. The middle gear portion 112 may have an outer diameter of about 0.8 mm (about 0.03 inches), and the teeth 113 of the middle gear portion may have a pitch diameter of about 0.6 mm (about 0.02 inches) and a pressure angle of about 20 degrees. Other dimensions of the pinion gear 104 are also envisioned. A first pair of jewel bearings 116 are received around the proximal and distal end portions 108, 110, respectively, of the pinion gear 104 and facilitate rotation of the pinion gear in the junction box 15.

The coil gear 106 includes a distal attachment portion 118, a proximal portion 120, and a middle gear portion 122. The distal attachment portion 118 is attached to the outer layer 12. In particular, a section of the distal attachment portion 118 is received in a proximal end of the outer layer 12 and fixedly attached thereto. In the illustrated embodiment, the middle gear portion 122 includes seventeen (17) teeth 123. The middle gear portion 122 may have an outer diameter of about 1.3 mm (about 0.05 inches). The teeth 123 of the middle gear portion 122 may have a pitch diameter of about 1.1 mm (about 0.04 inches) and a pressure angle of about 20 degrees. Other dimensions of the coil gear 106 are also envisioned.

In one embodiment, the gear assembly 92 has a gear ratio of between about 1 to 1 and about 2 to 1. In one embodiment, the gear assembly 92 has a gear ratio of about 1.7 to 1. The coil gear 106 having a greater number of teeth than the pinion gear 104 means that the gear assembly 92 will decrease the rotation speed of the coil gear 106 and outer layer 12 as compared to the rotation speed of the drive 48 and pinion gear 104. However, the decreased rotation speed will result in an increased force or torque output. Therefore, the coil gear 106, and thus the outer layer 12 and tissue-removing element 20, will rotate with an increased force/torque as compared to the drive 48. This will allow the tissue-removing element 20 to better remove occlusive tissue in the body lumen to separate the tissue from the wall of the body lumen.

A second pair of jewel bearings 124 are received around the distal and proximal end portions 118, 120, respectively, of the coil gear 106 and facilitate rotation of the coil gear in the junction box 15. A passage 126 extends through the coil gear 106 and receives a proximal end portion of the inner liner 14. The first bearing holder 100 is disposed around the bearings 116, 124 around the proximal end portions 108, 120 of the gears 104, 106, and the second bearing holder 102 is disposed around the bearings 116, 124 around the distal end portions 110, 118 of the gears. The bearings 116, 124 can be made from bronze. However, other materials are also envisioned. For example, the bearings can also be made from zirconia.

The housing 90 of the junction box 15 is sized such that the catheter 10 can be received within a guide catheter 128 so a clearance (FIG. 7) is provided on opposite lateral sides of the junction box to allow for saline or contrast media perfusion between the guide catheter 128 and the catheter 10. In particular, the center portion 94 of the housing 90 has planar side surfaces which create clearance spaces 129 between the sides of the center portion and the curved inner wall of the guide catheter 128. In one embodiment, the housing 90 is sized so that the catheter 10 can be received in a 7 F (about 2 mm) or smaller diameter guide catheter. In another embodiment, the housing 90 is sized so that the catheter 10 can be received in a 6 F (about 1.8 mm) or smaller diameter guide catheter.

Referring to FIGS. 6-8, a fluid port 130 may be provided in the drive tube 27 for introducing flushing/lubrication fluid into the gear assembly 92. In the illustrated embodiment, the port 130 is located in the distal end portion of the drive tube 27 and is disposed in registration with the proximal attachment portion 108 of the pinion gear 104. Fluid that is introduced at the proximal end of the catheter 10 is delivered through the guide catheter 128 and can be directed into the fluid port 130 and delivered to the middle gear portion 112 of the pinion gear 104 where rotation of the pinion gear transfers the fluid around the pinion gear and to the middle gear portion 122 of the coil gear 106. Rotation of the coil gear, caused by rotation of the pinion gear 104, moves the fluid around the coil gear 106 and transports the fluid to the distal attachment portion 118 of the coil gear where the fluid can be introduced into the space between the sheath 22 and the outer layer 12. Thus, the gear assembly 92 in the junction box 15 is configured to transport fluid from a proximal end of the junction box to a distal end of the junction box to cool the gear assembly 92 with the fluid. Additionally, by delivering fluid through the junction box 15 fluid introduced at the proximal end of the junction box can be transported to the distal end of the junction box and pumped into the space between the sheath 22 and the outer layer 12. Additionally, the asymmetrical configuration of the bearing holders 100, 102 facilitate the flow of fluid from the proximal end of the junction box 15 to the distal end.

Referring to FIGS. 5, 8, and 9, a sleeve 132 may also be disposed around the proximal end portion 120 of the coil gear 106. The sleeve 132 is configured to reduce friction on the coil gear 106 created by a push force caused from advancing the catheter 10 through the body lumen. The sleeve 132 may be made of graphite or some other low friction material. The sleeve 132 is configured to erode away in response to the push force experienced at the coil gear 106 during use of the catheter 10. By lowering the friction force around the coil gear 106 the efficiency of the junction box 15 is maximized.

Referring to FIGS. 1-4, and 15, the outer sheath 22 comprises a tubular sleeve configured to isolate and protect a subject's arterial tissue within a body lumen from the rotating outer layer 12. The inner diameter of the sheath 22 is sized to provide clearance for the outer layer 12. The space between the sheath 22 and the outer layer 12 allows for the outer layer to rotate within the sheath and provides an area for saline perfusion between the sheath and outer layer. In one embodiment, the sheath 22 has an inner diameter of about 0.050 inches (1.27 mm) and an outer diameter of about 0.055 inches (1.4 mm). The sheath 22 can have other dimensions without departing from the scope of the disclosure. In one embodiment, the outer sheath 22 is made from polytetrafluorethylene (PTFE). Alternatively, the outer sheath 22 may comprise a multi-layer construction. For example, the outer sheath 22 may comprise an inner layer of perfluoroalkox (PFA), a middle braided wire layer, and an outer layer of Pebax.

Referring to FIGS. 1-4, 14, and 15, the outer layer 12 may comprise a tubular stainless steel coil configured to transfer rotation and torque from the motor 43 and gear assembly 92 to the tissue-removing element 20. Configuring the outer layer 12 as a coiled structure provides the outer layer with a flexibility that facilitates delivery of the catheter 10 through the body lumen. Also, the coil configuration allows for the rotation and torque of the outer layer 12 to be applied to the tissue-removing element 20 when the catheter 10 is traversed across a curved path. The stiffness of the outer layer 12 also impacts the ease at which the coil is traversed through the body lumen as well as the coil's ability to effectively transfer torque to the tissue-removing element 20. In one embodiment, the outer layer 12 is relatively stiff such that axial compression and extension of the coil is minimized during movement of the catheter 10 through a body lumen. The coil configuration of the outer layer 12 is also configured to expand its inner diameter when the coil is rotated so that the outer layer remains spaced from the inner liner 14 during operation of the catheter 10. In one embodiment, the outer layer 12 has an inner diameter of about 0.023 inches (0.6 mm) and an outer diameter of about 0.035 inches (0.9 mm). The outer layer 12 may have a single layer construction. For example, the outer layer may comprise a 7 filar (i.e., wire) coil with a lay angle of about 30 degrees. Alternatively, the outer layer 12 could be configured from multiple layers without departing from the scope of the disclosure. For example, the outer layer 12 may comprise a base coil layer and a jacket (e.g., Tecothane™) disposed over the base layer. In one embodiment, the outer layer comprises a 15 filar coil with a lay angle of about 45 degrees. The Tecothane™ jacket may be disposed over the coil. Alternatively, the outer layer 12 may comprise a dual coil layer configuration which also includes an additional jacket layer over the two coil layers. For example, the outer layer may comprise an inner coil layer comprising a 15 filar coil with a lay angle of about 45 degrees, and an outer coil layer comprising a 19 filar coil with a lay angle of about 10 degrees. Outer layer having other configurations are also envisioned.

Referring to FIGS. 1-4 and 14-16, the inner liner 14 comprises a multiple layer tubular body configured to isolate the guidewire 26 from the coil gear 106, outer layer 12, and tissue-removing element 20. The inner liner 14 is extendable through the junction box 15 to the distal end of the catheter 10. In one embodiment, the inner liner 14 is fixedly attached to the junction box 15. The inner liner 14 has an inner diameter that is sized to pass the guidewire 26. The inner liner 14 protects the guide wire from being damaged by the rotation of the coil gear 106 and outer layer 12 by isolating the guidewire from the rotatable coil gear and outer layer. The inner liner 14 also extends past the tissue-removing element 20 to protect the guidewire 26 from the rotating tissue-removing element. Thus, the inner liner 14 is configured to prevent any contact between the guidewire 26 and the components of the catheter 10 that rotate around the guidewire. Therefore, any metal-to-metal engagement is eliminated by the inner liner 14. This isolation of the coil gear 106, outer layer 12, and tissue-removing element 20 from the guidewire 26 also ensures that the rotation of the outer layer and tissue-removing element is not transferred or transmitted to the guidewire. As a result, a standard guidewire 26 can be used with the catheter 10 because the guidewire does not have to be configured to withstand the torsional effects of the rotating components. Additionally, by extending through the tissue-removing element 20 and past the distal end of the tissue-removing element, the inner liner 14 stabilizes the tissue-removing element by providing a centering axis for rotation of the tissue-removing element about the inner liner.

In the illustrated embodiment, the inner liner 14 comprises an inner PTFE layer 60 an intermediate braided layer 62 comprised of stainless steel, and an outer layer 64 of polyimide. The PTFE inner layer 60 provides the inner liner 14 with a lubricous interior which aids in the passing of the guidewire 26 though the inner liner. The braided stainless steel intermediate layer 62 provides rigidity and strength to the inner liner 14 so that the liner can withstand the torsional forces exerted on the inner liner by the outer layer 12. In one embodiment, the intermediate layer 62 is formed from 304 stainless steel. The outer polyimide layer 64 provides wear resistance as well as having a lubricous quality which reduces friction between the inner liner 14 and the outer layer 12. Additionally, a lubricious film, such as silicone, can be added to the inner liner 14 to reduce friction between the inner liner and the outer layer 12. In one embodiment, the inner liner 14 has an inner diameter ID of about 0.016 inches (0.4 mm), an outer diameter OD of about 0.019 inches (0.5 mm), and a length of between about 7.9 inches (about 200 mm) and about 15.7 inches (400 mm). The inner diameter ID of the inner liner 14 provide clearance for the standard 0.014-inch guidewire 26. The outer diameter OD of the inner liner 14 provides clearance for the coil gear 106, outer layer 12, and tissue-removing element 20. Having a space between the inner liner 14 and the outer layer 12 reduces friction between the two components as well as allows for saline perfusion between the components.

In the illustrated embodiment, a marker band 66 (FIG. 2) is provided on an exterior surface of the distal end of the inner liner 14. The marker band 66 configures the tip of the inner liner 14 to be fluoroscopically visible which allow a physician to verify the position of the liner during a medical procedure. In this embodiment, the distal end of the inner liner 14 may be laser cut to provide a low profile tip. In one embodiment, the marker band 66 comprises a strip of platinum iridium.

Referring to FIGS. 1, 2, and 17, the tissue-removing element 20 extends along the first longitudinal axis LA1 from a proximal end adjacent the distal end portion of the outer layer 12 to an opposite distal end. The tissue-removing element 20 is operatively connected to the motor 43 for being rotated by the motor. When the catheter 10 is inserted into the body lumen and the motor 43 is activated to rotate the drive 48, which rotates the gear assembly 92 which then transfers the motor torque to the outer layer 12 thereby rotating the tissue-removing element 20, the tissue-removing element is configured to remove occlusive tissue in the body lumen to separate the tissue from the wall of the body lumen. Any suitable tissue-removing element for removing tissue in the body lumen as it is rotated may be used in one or more embodiments. In one embodiment, the tissue-removing element 20 comprises an abrasive burr configured to abrade tissue in the body lumen when the motor 43 rotates the abrasive burr. The abrasive burr 20 may have an abrasive outer surface formed, for example, by a diamond grit coating, surface etching, or the like. In one embodiment, the tissue-removing element comprises a stainless steel spheroid body with an exterior surface including 5 μm of exposed diamond crystals. The tissue-removing element 20 may also be radiopaque to allow the tissue-removing element to be visible under fluoroscopy. In other embodiments, the tissue-removing element can comprise one or more cutting elements having smooth or serrated cutting edges, a macerator, a thrombectomy wire, etc.

A cavity 72 extends longitudinally through the tissue-removing element 20 such that the tissue-removing element defines openings at its proximal and distal ends. The cavity 72 receives a portion of the outer layer 12 for mounting the tissue-removing element 20 to the outer layer. The cavity 72 includes a first diameter portion 74 extending from the proximal end of the tissue-removing element 20, a tapered diameter portion 76 extending from the first diameter portion toward the distal end of the tissue-removing element, and a second diameter portion 78 extending from the tapered diameter portion to the distal end of the tissue-removing element. The diameters of the first and second diameter portions 74, 78 are constant along their lengths. In the illustrated embodiment, a diameter D1 of the first diameter portion 74 is larger than a diameter D2 of the second diameter portion 78. In one embodiment, the diameter D1 of the first diameter portion 74 is about 0.035 inches (0.9 mm), and the diameter D2 of the second diameter portion 78 is about 0.022 inches (0.56 mm). The tapered diameter portion 76 provides a transition between the first and second diameter portions 74, 78. The outer layer 12 is received in the first diameter portion 74 and a distal end of the outer layer abuts the tapered diameter portion 76. The tissue-removing element 20 can be fixedly attached to the distal end of the outer layer 12 by any suitable means. In one embodiment an adhesive bonds the tissue-removing element 20 to the outer layer 12. The inner liner 14 extends through the outer layer 12 and the second diameter portion 78 of the tissue-removing element 20. The second diameter portion 78 is sized to pass the inner liner 14 with a small clearance. The inner diameter D2 provides clearance between the tissue-removing element 20 and inner liner 14 to reduce friction between the components and allow a space for saline perfusion. Accordingly, the tissue-removing element 20 is shaped and arranged to extend around at least a portion of the outer layer 12 and inner liner 14 and thus provides a relatively compact assembly for abrading tissue at the distal end portion of the catheter 10.

The exterior surface of the tissue-removing element 20 includes a proximal segment 80, a middle segment 82, and a distal segment 84. A diameter of the proximal segment 80 increases from the proximal end of the tissue-removing element 20 to the middle segment 82. The middle segment has a constant diameter and extends from the proximal segment 80 to the distal segment 84. The diameter of the distal segment 84 tapers from the middle segment 82 to the distal end of the tissue-removing element 20. The tapered distal segment 84 provides the tissue-removing element 20 with a general wedge shape configuration for wedging apart constricted tissue passages as it simultaneously opens the passage by removing tissue using the abrasive action of the tissue-removing element. The distal end of the tissue-removing element 20 is also rounded to provide the tissue-removing element with a blunt distal end.

Referring to FIGS. 1 and 2, to remove tissue in the body lumen of a subject, a practitioner inserts the guidewire 26 into the body lumen of the subject, to a location distal of the tissue that is to be removed. Subsequently, the practitioner inserts the proximal end portion of the guidewire 26 through the distal end of the guidewire lumen 24 of the inner liner 14 and through the junction box 15 so that the guidewire extends through the guidewire port 39 in the junction box to exit the catheter 10. The guidewire port 39 allows the catheter 10 to be used in a rapid exchange and single operator exchange procedures. With the catheter 10 loaded onto the guidewire 26, the practitioner advances the catheter along the guidewire until the tissue-removing element 20 is positioned proximal and adjacent the tissue. When the tissue-removing element 20 is positioned proximal and adjacent the tissue, the practitioner actuates the motor 43 using the actuator 42 to rotate the drive 48, the gear assembly 92, the outer layer 12, and the tissue-removing element mounted on the outer layer. The tissue-removing element 20 abrades (or otherwise removes) the tissue in the body lumen as it rotates. While the tissue-removing element 20 is rotating, the practitioner may selectively move the catheter 10 distally along the guidewire 26 to abrade the tissue and, for example, increase the size of the passage through the body lumen. The practitioner may also move the catheter 10 proximally along the guidewire 26, and may repetitively move the components in distal and proximal directions to obtain a back-and-forth motion of the tissue-removing element 20 across the tissue. During the abrading process, the inner liner 14 isolates the guidewire 26 from the rotating coil gear 106, outer layer 12, and tissue-removing element 20 to protect the guidewire from being damaged by the rotating components. As such, the inner liner 14 is configured to withstand the torsional and frictional effects of the rotating coil gear 106, outer layer 12, and tissue-removing element 20 without transferring those effects to the guidewire 26. When the practitioner is finished using the catheter 10, the catheter can be removed from the body lumen. Because the guidewire lumen 24 is considerably shorter than the overall length of the catheter 10, the catheter can be removed from the body lumen in a rapid exchange or single operator exchange procedure without pulling the guidewire 26 out of the body lumen together with the catheter because the length of the guidewire protruding from the subject is longer than the length of the guidewire lumen 24 of the catheter. Thus, at least a portion of the guidewire 26 is exposed at all times and may be grasped by the practitioner.

Referring to FIGS. 18-24, a catheter of another embodiment is generally indicated at 10′. The catheter 10′ includes a junction box 15′ similar to the junction box 15 of the first embodiment. The junction box 15′ comprises a housing 90′ enclosing a gear assembly 92′ for operatively connecting a drive 48′ to an outer layer 12′. The housing 90′ comprises a center portion 94′ which generally surrounds the gear assembly 92′, and proximal and distal end portions 96′ which provide a strain relief function for the housing to alleviate tension applied to the proximal and distal ends of the junction box 15′ as the catheter 10′ is bent during use.

The gear assembly 92 comprises a pinion gear 104′ in mesh with a coil gear 106′. The pinion gear 104′ is attached to the drive 48′ such that rotation of the drive causes rotation of the pinion gear which in turn rotates the coil gear 106′. The coil gear is attached to the outer layer 12′ such that rotation of the coil gear causes rotation of the outer layer. The pinion gear 104′ comprises a proximal attachment portion 108′, a distal end portion 110′, and a middle gear portion 112′. The drive 48′ is received in the proximal attachment portion 108′. The drive 48′ is fixed within the proximal attachment portion 108′ to attach the drive to the pinion gear 104′. In the illustrated embodiment, the middle gear portion 112′ includes eight (8) teeth 113′. The middle gear portion 112′ may have an outer diameter of about 0.8 mm (about 0.03 inches), and the teeth 113′ of the middle gear portion may have a pitch diameter of about 0.6 mm (about 0.02 inches) and a pressure angle of about 20 degrees. Other dimensions of the pinion gear 104′ are also envisioned.

The coil gear 106′ includes an attachment portion 118′ and a gear portion 122′. A passage 126′ extends through the coil gear 106′ and receives proximal end portions of the outer layer 12′ and inner liner 14′. The attachment portion 118′ is attached to the proximal end of the outer layer 12′. In particular, the outer layer 12′ is received in the attachment portion 118′ of the coil gear 106′ and fixedly attached thereto. In the illustrated embodiment, the gear portion 122′ includes fourteen (14) teeth 123′. The gear portion 122′ may have an outer diameter of about 1.3 mm (about 0.05 inches). The teeth 123′ of the gear portion 122′ may have a pitch diameter of about 1.1 mm (about 0.04 inches) and a pressure angle of about 20 degrees. Other dimensions of the coil gear 106′ are also envisioned. In one embodiment, the gear assembly 92′ has a gear ratio of between about 1 to 1 and about 2 to 1. In one embodiment, the gear assembly 92′ has a gear ratio of about 1.75 to 1.

A first bearing 116′ is received around the proximal end portion 108′ of the pinion gear 104′ and the inner liner 14′. The first bearing 116′ includes a first hole for receiving the proximal end portion 108′ of the pinion gear 104′, and a second hole for receiving the inner liner 14′. A second bearing 124′ is received around the distal end portions 110′, 118′ of the pinion gear 104′ and coil gear 106′, respectively. The second bearing 124′ includes a first hole for receiving the distal end portion 110′ of the pinion gear 104′, and a second hole for receiving the distal end portion 118′ of the coil gear 106′. The bearings 116′, 124′ can be made from bronze. However, other materials are also envisioned. For example, the bearings 116′, 124′ can also be made from zirconia.

When introducing elements of the present invention or the one or more embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As various changes could be made in the above apparatuses, systems, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

What is claimed is:
 1. A tissue-removing catheter for removing tissue in a body lumen, the tissue-removing catheter comprising: a tube extending axially along the catheter; a junction box housing located at a distal end of the tube; an elongate body extending distally from the junction box housing, the elongate body being sized and shaped to be received in the body lumen; a gear assembly disposed in the junction box housing, the gear assembly engaging the elongate body for rotating the elongate body; and a tissue-removing element mounted on a distal end portion of the elongate body, the tissue-removing element being configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen.
 2. A tissue-removing catheter as set forth in claim 1, further comprising a handle mounted at a proximal end portion of the tube and operable to cause rotation of the elongate body.
 3. A tissue-removing catheter as set forth in claim 1, further comprising an inner liner received within the elongate body, the inner liner defining at least a portion of a guidewire lumen.
 4. A tissue-removing catheter as set forth in claim 3, further comprising a motor in the handle, wherein the tube comprises a drive tube engaging the gear assembly for rotating the gear assembly to rotate the elongate body and tissue-removing element mounted on the elongate body.
 5. A tissue-removing catheter as set forth in claim 4, wherein the drive tube defines a longitudinal axis that is parallel to and spaced apart from a longitudinal axis of the elongate body.
 6. A tissue-removing catheter as set forth in claim 4, further comprising an actuator positioned on the handle and configured to selectively actuate the motor to drive rotation of the elongate body and tissue-removing element.
 7. A tissue-removing catheter as set forth in claim 4, wherein the gear assembly comprises a first gear fixedly attached to the drive tube, and a second gear in mesh with the first gear and fixedly attached to the elongate body such that rotation of the drive tube causes rotation of the first gear which in turn rotates the second gear thereby causing rotation of the elongate body.
 8. A tissue-removing catheter as set forth in claim 7, wherein the second gear defines a passage for receiving the inner liner.
 9. A tissue-removing catheter as set forth in claim 7, where the first gear is a pinion gear and the second gear is a coil gear.
 10. A tissue-removing catheter as set forth in claim 7, further comprising a sleeve disposed around a proximal end portion of the second gear to reduce friction on the second gear created by a push force caused from advancing the catheter through the body lumen.
 11. A tissue-removing catheter as set forth in claim 7, wherein the drive tube defines a fluid port for introducing fluid into the gear assembly.
 12. A tissue-removing catheter as set forth in claim 11, wherein the fluid port is located in a distal end portion of the drive tube.
 13. A tissue-removing catheter as set forth in claim 11, wherein the fluid is delivered to the first gear whereby rotation of the first gear transfers the fluid around the first gear and to the second gear.
 14. A tissue-removing catheter as set forth in claim 13, wherein rotation of the second gear moves the fluid around the second gear and transports the fluid to the elongate body.
 15. A tissue-removing catheter as set forth in claim 14, further comprising an outer sheath disposed around the elongate body, the fluid being introduced into a space between the outer sheath and the elongate body.
 16. A tissue-removing catheter as set forth in claim 3, wherein a distal end of the inner liner extends distally of the tissue-removing element.
 17. A tissue-removing catheter as set forth in claim 1, wherein the gear assembly in the junction box housing is configured to transport fluid from a proximal end of the junction box housing to a distal end of the junction box housing to cool the gear assembly with the fluid.
 18. A tissue-removing catheter as set forth in claim 1, wherein the junction box housing comprises a rigid center portion generally surrounding the gear assembly, and flexible proximal and distal end portions.
 19. A tissue-removing catheter as set forth in claim 18, wherein the rigid center portion comprises a casing and a first bearing holder mounted on a proximal end of the casing and a second bearing holder mounted on a distal end of the casing.
 20. A tissue-removing catheter as set forth in claim 1, wherein the tissue-removing element comprises an abrasive burr. 